Question detail
During a practical investigation, a student notices that a reaction between a solid and a gas is slower when the solid is in a single block rather than a finely divided powder. Which principle best explains this observation?
Try the question, check the answer, then read the explanation to understand the curriculum point.
At a glance
MCQ
Type
practice
Style
Topic
Rate of reaction
Question
- A. The gas pressure is lower around the block.
- B. The surface area of the solid is smaller in the block form.
- C. The solid in block form has a higher activation energy.
- D. The reaction is endothermicand slower at lower temperatures.
Answer
The surface area of the solid is smaller in the block form.
Explanation
The correct answer is The surface area of the solid is smaller in the block form.. This answer directly addresses the question: During a practical investigation, a student notices that a reaction between a solid and a gas is slower when the solid is in a single block rather than a finely divided powder. Which principle best explains this observation? It matches the approved Chemistry 8462 learning objective and the linked subtopic. The other options are incorrect because they either change the rate, catalyst, reversible reaction, equilibrium, or graph context, or they do not answer the exact point being tested.
Common mistake
Misunderstanding Surface Area Effect
Students often think that increasing surface area speeds up reactions because it increases the amount of reactant rather than the number of exposed particles available for collisions.
Emphasize that increasing surface area allows more particles to be exposed and available for collisions, which increases the frequency of collisions and thus the reaction rate.
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